An image projection apparatus is known in which an image generation unit generates an image based on image data received from a personal computer (PC) or a digital camera using light emitted by a light source, and the generated image is passed through an optical system including a plurality of lenses to project an image on a screen. For example, a liquid crystal display (LCD) panel or a digital micromirror device (DMD) may be used as the image generation unit.
As a measure to increase the resolution of a projection image of the image projection apparatus, increasing the density of picture elements in the image generation unit is conceivable. However, the manufacturing cost of the image generation unit will increase. To avoid this, an image projection apparatus is proposed in which decentered lenses provided in a projection optical system are moved to shift a projection image on the plane of projection so that the resolution of the projection image is increased. For example, see Japanese Laid-Open Patent Publication No. 2005-084581.
However, it is necessary to provide an additional mechanism for moving the decentered lenses in the projection optical system of the proposed image projection apparatus of Japanese Laid-Open Patent Publication No. 2005-084581. The projection optical system must have a complicated structure and the degree of flexibility of the design will be reduced. Moreover, it is difficult to control the positions of the decentered lenses at high speed and with good accuracy. Specifically, it is difficult to increase the resolution of the projection image by shifting the projection image on the plane of projection through the controlled movement of the decentered lenses by a distance which is less than an interval between two of the picture elements of the image generation unit.